Ant Colonies Earn Their 'Superorganism' Reputation

In an ant colony, every ant has their job to do according to their caste. The queens make babies, the soldiers defend the nest, the workers forage for food (or steal it), and some ants, mysteriously, work at nothing all day. In some species, the different castes even have different body types and sets of behaviors that help them do their jobs, and they cooperate to keep the colony humming along smoothly and to ensure the survival of the whole group. Their intense collectivism allows them to build rafts made of themselves and flow like ketchup as if transitioning between solid and liquid states.

It’s a way of life that’s led scientists to think of ant colonies and other insect societies as “superorganisms” instead of just groups of individuals living together. The different ants and castes are less like people in a city and more like the cells and organs in a body. Biologist Thomas O’Shea-Wheller’s recent research, published in PLOS ONE, shows that ant colonies well deserve that nickname, reacting to threats “much like a single organism would in response to attacks on different parts of its body,” he writes.

When an individual animal is in danger, its reaction depends on the type and origin of the threat. If you touched a hot stove burner, for example, you’d pull your hand away. If the stove set your kitchen on fire, though, you’d probably run out of the house to safety. To see if ant colonies respond similarly, O’Shea-Wheller and his research team at the University of Bristol subjected the insects to mock attacks on different parts of their colonies. They worked with the species Temnothorax albipennis, because these ants spend their time in different locations in and around the nest according to their roles, giving the researchers the opportunity to attack the superorganism’s different “body parts.”

The team collected 30 ant colonies from a quarry in Dorset, England, and transferred them to their lab. Once the ants were settled into their new homes, the researchers simulated predator attacks by scooping up certain worker ants with a tiny brush and removing them from the colonies. In some attacks, they removed scouts that were leaving the nests or walking around the periphery, while in others they pulled the tops off the nests and kidnapped ants from their centers.

The colonies responded differently to the various types of attacks. When scouts were removed, other ants retreated inside the nest and the colony slowed or stopped the exit of new scouts. The reaction is similar to the withdrawal reflex a single organism might show in response to injuring a limb, the researchers say. Meanwhile, when ants were removed from the center of the nest, the whole colony picked up and moved out, coordinating a mass evacuation of the nest and moving to a new one—all while protecting the queen, eggs, and larvae.

In both of these situations, the ants reacted collectively to the loss of just a few workers in ways that were specific to the location of the attacks. In other words, they dealt with injuries to their "extremities" and their "heart" in different ways.

“Superorganisms may benefit from reacting as a single entity to the threat of predation,” the researchers write. "This highlights the propensity for ant colonies to employ a multi-organismal ‘nervous system’ to deal with challenges.”

Bivalves like mussels, clams, and oysters aren’t good swimmers, and they don’t have teeth. Their hard shells are often the only things standing between themselves and a sea of dangers.

But even those shells have been threatened lately, as pollution and climate change push the ocean's carbon dioxide to dangerous levels. Too much carbon dioxide interferes with a bivalve’s ability to calcify (or harden) its shell, leaving it completely vulnerable.

A team of German scientists wondered what, if anything, the bivalves were doing to cope. They studied two populations of blue mussels (Mytilus edulis): one in the Baltic Sea, and another in the brackish waters of the North Sea.

The researchers collected water samples and monitored the mussel colonies for three years. They analyzed the chemical content of the water and the mussels’ life cycles—tracking their growth, survival, and death.

The red line across this mussel larva shows the limits of its shell growth. Image credit: Thomsen et al. Sci. Adv. 2017

Analysis of all that data showed that the two groups were living very different lives. The Baltic was rapidly acidifying—but rather than rolling over and dying, Baltic mussels were armoring up. Over several generations, their shells grew harder.

Their cousins living in the relatively stable waters of the North Sea enjoyed a cushier existence. Their shells stayed pretty much the same. That may be the case for now, the researchers say, but it definitely leaves them vulnerable to higher carbon dioxide levels in the future.

"Future experiments need to be performed over multiple generations," the authors write, "to obtain a detailed understanding of the rate of adaptation and the underlying mechanisms to predict whether adaptation will enable marine organisms to overcome the constraints of ocean acidification."

The future of diabetes medicine may be duck-billed and web-footed. Australian researchers have found a compound in platypus venom (yes, venom) that balances blood sugar. The team published their results in the journal Scientific Reports.

So, about that venom. The platypus (Ornithorhynchus anatinus) may look placid and, frankly, kind of goofy, but come mating season, the weaponry comes out. Male platypuses competing for female attention wrestle their opponents to the ground and kick-stab them with the venom-tipped, talon-like spurs on their back legs. It’s not a pretty sight. But it is an interesting one, especially to researchers.

Animal venoms are incredible compounds with remarkable properties—and many of them make excellent medicine. Many people with diabetes are already familiar with one of them; the drug exenatide was originally found in the spit of the venomous gila monster. Exenatide works by mimicking the behavior of an insulin-producing natural compound called Glucagon-like peptide 1 (GLP-1). The fact that the lizard has both venom and insulin-making genes is not a coincidence; many animal venoms, including the gila monster’s, induce low blood sugar in their prey in order to immobilize them.

It’s a good strategy with one flaw: GLP-1 and compounds like it break down and stop working very quickly, and people who have trouble making insulin really need their drug to keep working.

With this issue in mind, Australian researchers turned their attention to our duck-billed friends. They knew that platypuses, like people, made GLP-1 in their guts, and that platypuses, like gila monsters, make venom. The real question was how these two compounds interacted within a platypus’s body.

The researchers used chemical and genetic analysis to identify the chemical compounds in the guts and spurs of platypuses and in the guts of their cousins, the echidnas.

They found something entirely new: a tougher, more resilient GLP-1, one that breaks down differently—and more slowly—than the compounds in gila monster spit. The authors say this uber-compound is the result of a "tug of war" between GLP-1’s two uses in the gut and in venom.

"This is an amazing example of how millions of years of evolution can shape molecules and optimise their function," co-lead author Frank Gutzner of the University of Adelaide said in a statement.

"These findings have the potential to inform diabetes treatment, one of our greatest health challenges, although exactly how we can convert this finding into a treatment will need to be the subject of future research."